Agave infiernilloensis Etter, Kristen, Rosales & A.Vázquez, 2022

Etter, Julia, Kristen, Martin, Rosales-Martínez, C. Santiago & Vázquezgarcía, J. Antonio, 2022, Agave infiernilloensis (sect. Choritepalae, Asparagaceae), a gigantic new species from the Balsas Basin in Western Mexico, Phytotaxa 564 (2), pp. 208-220 : 211-215

Agave infiernilloensis Etter, Kristen, Rosales & A.Vázquez , sp. nov. ( Figs. 1–3 ).

Diagnosis: Agave infiernilloensis shares with A. gypsicola a similar leaf shape and flower type (choritepalous), however, it differs from the latter in having larger rosettes, larger pale green to yellowish-green leaves, shorter and recurving inflorescence, shorter terminal spines, more flowers per node and longer ovaries ( Table 1 ).

Type: — MEXICO: Michoacán, municipality of Múgica, Mex 37 D Nueva Italia – Uruapan , near the Francisco J. Múgica Dam, on cliffs of igneous rocks of west exposure of the northern side of Puente Begoña (barranca Begoña), 338 m, 19°01’53.82’’N, 102°03’11.08’’W, over rocky outcrops in tropical dry forest, 21 December 2020 (fl), J. Etter and M. Kristen 4775 (holotype: IBUG!, isotypes: CIMI!, IEB!) .

Plants perennial, acaulescent, single, symmetrical; rosettes open, 170–210 cm diameter, 115–120 (–150) cm in height, not offsetting. Leaves 18–24 (–30) per rosette, (75–) 100–125 × 36–42 (–49) cm, widely ovate, narrowed at the base of 17–22 × 6–10 cm, deeply channeled at the widest part in the proximal 1/2–2/3 of leaf length, arching outside towards the apex, abaxially pale bluish-green to glaucous-gray, showing leaf imprint from newer leaves, adaxially pale green to yellowish green or light bluish-glaucous, sometimes with waxy sheen, fibrous and succulent; leaf margin nearly smooth to finely denticulate, whitish to pale yellowish in young leaves, reddish-brown in older leaves; denticles usually 3–6 per cm, 1–1.5 × 1–1.5 mm, of the same color as the margin or grayish in older leaves; terminal spine 5–6 mm or inconspicuous, reddish-brown, sometimes drying fast. Inflorescence spiciform, 230–380 × 19.6 cm, recurving, peduncle, 65–80 × 4.5–5.5 cm in diameter at the base, bracts of the peduncle long linear with a deltoid base, fertile part 165–300 cm long, densely flowered, with multiple nodes; peduncle of node 5–7 mm long, pedicels 7–9 mm long, flower bractlets inconspicuous, ca. 2 mm long, triangular, united at the proximal 1/3–1/2 of the pedicel length; flowers 3–4 per node, 40–50 mm long, protandrous; tube absent, replaced by a discoid receptacle; tepals distinct, recurving slightly hooded at the tips, creamy to greenish-white, usually lighter towards the border; ovary 24 mm long, green, oblong, neck constricted; filaments 39–47 mm long, white, greenish at the proximal part; anthers 1.4–1.5; style shorter than the filaments during the male phase, 31–33 mm long, elongating as long as the filaments or longer during the female phase; stigma capitate; capsules ellipsoid, 2.3–2.6 × 0.8–1.1 cm, constricted at the base and apex, tip apiculate, peduncle of node 1.2–1.3 cm long, pedicels 1–1.2 cm long; seeds 4–5 × 3–4 mm, lunulate, black.

Distribution and ecology: — Agave infiernilloensis is known only from extrusive igneous outcrops around Presa Infiernillo, in the Zicuirán-Infiernillo Biosphere Reserve, and Presa Francisco J. Múgica, 4 km east of Nueva Italia, both localities in the state of Michoacán within the Balsas Basin biogeographic province. Its occurrence is confirmed by examining photographic or living material from four municipalities:Arteaga, Churumuco, La Huacana, and Múgica. These occurrences, vouchered by photographs, will soon be available at www.agavaceae.com ( Etter & Kristen 1997). Populations from La Salada (Nelson 6923) and Tuzantla presumably correspond to this species. It grows in the tropical deciduous forest at an elevation of 340–700 m, with Agave angustiarum Trel. in Standley (1920: 139), Backebergia militaris (Audot 1845: 307) Bravo ex Sánchez-Mejorada (1973: 174) , Bursera spp. , Ferocactus lindsayi Bravo-Hollis (1966: 9) , Hechtia glauca Burt-Utley & Utley (1993: 220) , Opuntia spp. , Plumeria rubra Linnaeus (1753: 209) , Stenocereus spp. , Selenicereus murrillii Britton & Rose (1920: 206) , and others. Flowering from November to January and fruiting from May to June.

Etymology and ethnobotany: —The species is named after Presa Infiernillo (“Little Hell”), also known as Presa Adolfo López Mateos, located between the states of Michoacán and Guerrero, where the species was first found on rocky outcrops of steep slopes. It is locally known as “maguey silvestre” (wild agave) or “flor de laja” (flagstone flower). The fibers of the shaft are used to produce “cintos piteados”, embroidered belts. The species has potential as an ornamental in dry tropical areas.

Conservation status: — Agave infiernilloensis was assessed as Endangered (EN); it is extremely abundant but restricted to few locations (EOO of 848.72 km 2 and AOO of 24.00 km 2), meeting the criteria B1 and B2.

Additional specimens examined: — The specimens from MÉXICO: Michoacán, La Salada, 15–22 March 1903 (capsules), Nelson 6923 ( NY, US) presumably correspond to this species; further fieldwork is needed on this population to obtain flowering material .

Figures

FIGURE 1. Agave infiernilloensis. A. Shaft with bracts and terminal spine. B. Flower buds. C. Open flowers. D. Habit. E-G. Sequence from flower bud to mature flower. H. Node of four flowers about to start anthesis. I. Node of fully open flowers. J. Corneous leaf margin (upper portion). K. Denticulate leaf margin (lower portion). L. Leaf with printed margins. M. Rosette. Art illustration by Edgar Esau Vázquez-Verdejo.

FIGURE 2. Agave infiernilloensis. A. Rosette with recurving inflorescence. B and C. Plants growing over rocky outcrops. D. Distal inflorescence segment. E. Nodes showing buds and flowers. F. Flower. G. Inflorescence detail. Photographs by Julia Etter & Martin Kristen.

FIGURE 3. Agave infiernilloensis. A. Finely denticulate margin. B. Nearly smooth margin. C-D. Habitat. E. Lower face of the leaf. F. Rosette. G. Fruits. Photographs by Julia Etter & Martin Kristen.